The present invention relates to antenna couplers and, more particularly, to a verification device adapted for repeatable, accurate, and convenient verification of the operability of an antenna coupler prior to its use in testing an airplane's onboard transmitter or receiver.
The environment of the present invention is shown in FIG. 1. An aircraft, generally indicated as 10, has an onboard transmitter or receiver 12 connected to a plurality of transmitting or receiving antennas 14 by transmission lines 16. The antennas 14 are disposed within radomes 18, or the like, incorporated within the skin 20 of the aircraft 10. The transmission lines 16 include directional couplers such as indicated at 22. To test the continuity of the complete system including the antennas 14, transmission lines 16, directional couplers 22, and transmitter or receiver 12, a test antenna coupler such as that generally indicated as 24 is employed. Antenna coupler 24 comprises a can or housing 26 having a peripheral portion 28 adapted to fit closely to the skin 20 of the aircraft 10 adjacent to the antenna 14 to be tested. The peripheral portion 28 is shaped such that when fit against the contours of the skin 20, a test antenna 30 is placed in alignment with the antenna 14 to be tested. The test antenna 30 is mounted within an absorptive material 32 and is connected to a connector 34 by a cable 36. A boot 29 of suitable flexible material is disposed across the peripheral portion 28 to protect the test antenna 30 from exposure to foreign debris. The system test procedure comprises attaching appropriate test apparatus (not shown) to the connector 34 and injecting a signal into the system through cavity 50 and the antenna 14 by the test antenna 30. The return signal is then analyzed to determine the continuity of the antenna 14, transmission lines 16, directional couplers 22, and transmitter or receiver 12 being tested.
The problem addressed by the present invention is testing the tester--that is, the antenna coupler 24 and the test antenna 30 contained therein must be verified as to their correct operativeness before they are used to test the antennas 14 and connecting equipment of the complete system. According to prior art techniques, a device such as that labeled 38 in FIG. 2 has been employed. Verification device 38 comprises a head 40 containing a verification antenna 42 (shown ghosted in FIG. 3). The head 40 is connected to a handle 44 to which a test cable 46 is attached internally connected to the verification antenna 42. Appropriate electronic equipment (not shown) for verifying the correct operation of the antenna coupler is connected through cable 46. Typically, an indicia 48 is placed on the head 40 in alignment with the antenna 42. In use, verification device 38 is manually aligned with the test antenna 30 by using the indicia 48. While such a device serves the purpose of verifying the antenna coupler's 24 operation, it has not proven entirely satisfactory because it cannot be repeatably positioned.